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Enable functionality allowing I/O devices to be put into energy-saving
(low power) states at run time (or autosuspended) after a specified
period of inactivity and woken up in response to a hardware-generated
wake-up event or a driver's request.

Hardware support is generally required for this functionality to work
and the bus type drivers of the buses the devices are on are
responsible for the actual handling of the autosuspend requests and
wake-up events.